1. Field of the Invention
The present invention relates to a hydraulic pump in a power steering system, and more particularly, to a flow rate control device of a hydraulic pump in a power steering system, which can improve handling stability of a vehicle by reducing a flow rate discharged from the hydraulic pump when the vehicle is driven at high speed.
2. Description of Related Art
A known power steering system of a vehicle is a system that assists driver's handling force of a steering handle by using oil pressure. The oil pressure is generated by a flow rate discharged from a hydraulic pump.
A rotor having a plurality of centrifugal vanes is rotatably installed in a cam ring that is fixedly installed and when the rotor rotates by receiving rotation force of an engine, the vein projects by receiving centrifugal force, thereby changing the volume of a space between the cam ring and the rotor. Therefore, the hydraulic pump discharges fluid by a different in pressure.
However, the hydraulic pump is connected to the engine to be driven by receiving the rotation force of the engine, such that a fuel ratio of the engine is deteriorated. As the hydraulic pump is connected to the engine so that a rotation speed of the engine is the same as that of the hydraulic pump, a vehicle is driven at high speed, thus, the rotation speed of the engine increases and the hydraulic pump is operated at high speed. At this time, the flow rate discharged from the hydraulic pump increases and thus the oil pressure is also raised.
Accordingly, when the vehicle is driven at high speed, the oil pressure discharged from the hydraulic pump also increases, thereby assisting the handling force of a steering handle by the increased oil pressure at the time of handling the steering handle. As a result, a handling feeling of the steering handle becomes lighter, such that the handling stability of the vehicle deteriorates.
In order to solve the above-described disadvantage, the deterioration of the fuel ratio may be improved by adopting a variable capacity type hydraulic pump having a structure in which a cam moves by the internal pressure of the hydraulic pump, but in this case, manufacturing cost increases and the NVH performance of the vehicle deteriorates due to a complicated structure.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.